1. Field of the Invention
The present invention relates to a display apparatus for use in an information processing apparatus, a communications apparatus, a video apparatus, a game apparatus and an apparatus mounted in a ship or a vehicle.
2. Description of the Prior Art
Conventionally, portable personal computers use liquid crystal displays of TFT (thin film transistor) active matrix type where a plurality of dots are horizontally and vertically arranged in a matrix. To display images, the supply voltage is supplied from a battery to the liquid crystal display panel to cause a driver to perform scanning.
Specifically, as shown in FIG. 1, this liquid crystal display has a plurality of signal electrodes 1, scanning electrodes 2, TFTs 3 and dot electrodes 4 formed in a matrix on the side of one insulating substrate (not shown), has common electrodes 5 formed on the side of the other insulating substrate (not shown) opposite thereto, and has a liquid crystal layer between the common electrodes 5 and the dot electrodes 4. Display with the dots is performed by line sequential scanning by the signal electrodes 1 and the scanning electrodes 2.
For example, when a scanning voltage is applied from a gate driver 6 to the scanning electrode 2 in the first line, the TFTs 3 in the first line connected thereto are activated to connect the signal electrodes 1 to the dot electrodes 4 in the first line, so that a signal voltage (i.e. video signal) is applied from a source driver 7 to the dots in the first line. By repeating such an application operation (scanning) for every line from the first line at a horizontal period, one field of video signals is displayed on the liquid crystal display, and by repeating this application operation every field, i.e. at a vertical period, the image is reproduced. The signal voltage is inverted every line and every field so that no direct current component is added to the liquid crystal display.
A liquid crystal driving voltage used in such a display apparatus is high because of the necessity of high duty, and the supply voltage supplied to the liquid crystal display panel is comparatively high. This increases the power consumed while the image is being displayed, which is a problem when the display apparatus is used, for example, in a portable apparatus having a power source such as a battery whose capacity is limited.